1. Technical Field
The present invention relates to an illuminator and a projector.
2. Related Art
There has been a known illuminator including: a solid-state light source group formed of a plurality of solid-state light sources that produce excitation light and outputting the excitation light toward a predetermined light collection position; a phosphor layer that positions in the vicinity of the light collection position and produces fluorescence light when excited with the excitation light from the solid-state light source group; a collimator system that substantially parallelizes the light from the phosphor layer; and a lens integrator system that homogenizes the in-plane light intensity distribution of the light from the collimator system. There has also been a known projector including the illuminator (see JP-A-2004-327361, for example). The illuminator of the related art, which uses the excitation light produced by the plurality of solid-state light sources to produce fluorescence light, can produce high-intensity illumination light. Further, the illuminator of the related art, which includes a lens integrator system that uses light very efficiently as an optical integration system, can use light very efficiently to produce illumination light with little brightness unevenness.
The “lens integrator system” used herein is an optical integration system including a first lens array, a second lens array, and a superimposing lens. The lens integrator system, in which the first lens array divides light into a plurality of sub-light fluxes, and the second lens array and the superimposing lens superimpose the plurality of sub-light fluxes on an illuminated surface, can homogenize the in-plane light intensity distribution of the light.
The illuminator of the related art, which uses the excitation light produced by the plurality of solid-state light sources to produce fluorescence light, has a problem of a short life of the phosphor layer because a large thermal load is applied to the phosphor layer. There has been therefore a demand in the art of illuminator to use the light from a plurality of solid-state light sources as illumination light without using any phosphor layer. When the light from a plurality of solid-state light sources is used as illumination light without any phosphor layer, the light from each of the solid-state light sources is incident on a lens integrator system in the form of spot-shaped light because each of the solid-state light sources substantially can be considered as a point light source. Any lens integrator system, however, cannot homogenize the in-plane light intensity distribution of such spot-shaped light in a satisfactory manner, and the configuration of the illuminator of the relate art is therefore problematic in that producing high-intensity illumination light and producing illumination light with high efficiency along with little brightness unevenness cannot be satisfied at the same time.